A Swiss Mennonite family name, one of the earliest records of this name occurs in 1548 when Johannes Bair wrote a letter to the brotherhood in Moravia. This letter is found in the Martyrs' Mirror. The name was also found in Bavaria and Franconia. One of the earliest Baer arrivals in America was Jacob who reached Philadelphia 30 September 1727. Samuel Bär was preacher in the Immelhausen, Palatinate, congregation ca. 1766; about the same time Hans Bär served as a preacher in the Bockschaft congregation. Henry Baer was ordained minister in 1771 in the Swamp congregation in Bucks County, Pennsylvania.

Prominent in this family was Adam Baer (1826-1904), who was born in Lancaster County, Pennsylvania, and later moved to Washington County, Maryland, where he was ordained deacon and minister. Martin Baer (d. 1758) was a pioneer minister and bishop in the Mellinger district of Lancaster County, Pennsylvania. P. J. Boehr was a General Conference Mennonite missionary in India. John B. Baer (1854-1939) was a prominent minister in the General Conference Mennonite Church, who served as home missionary and field secretary of the General Conference for a period of 15 years.

Braght, Thieleman J. van. The Bloody Theatre or Martyrs' Mirror of the Defenseless Christians Who Baptized Only upon Confession of Faith and Who Suffered and Died for the Testimony of Jesus Their Saviour . . . to the Year A.D. 1660. Scottdale, PA: Herald Press, 1951. Available online at: http://www.homecomers.org/mirror/index.htm.